1. Field of the Invention
The present invention relates to liquid transfer devices used in laboratories and, more particularly, is directed toward electronic pipetting devices.
2. Description of the Prior Art
Pipettes are precision glass or plastic tubes which are used in laboratories for the transfer of relatively small quantities of liquids, for example quantity to 100 ml, typically 0.01 ml to 50 ml, and specifically 0.1 to 30 ml. The pipette is used by placing it into a reservoir (flask, beaker, etc.) of liquid and creating suction via a mechanical device or one's mouth to draw liquid into the pipette. The mouth piece portion of the pipette is fitted with a cotton plug to protect the user from ingesting dangerous liquids or to prevent contamination of the mechanical system. By visually monitoring the level of liquid in the pipette accordingly to graduations printed thereon, the user is able to match the amount of liquid to the desired volume. Currently designed manual and electronic pipetting systems suffer from the disadvantage that the filling of pipettes to a precise level is a time consuming and tedious task. In addition, errors are caused by user inconsistencies. Furthermore, since a new pipette is often used for each liquid sample, precision made plastic or glass pipettes, which are costly to manufacture, are necessary to maintain consistency between pipettes. Current air displacement systems are calibrated to water at 20.degree. C. as the standard. A need exists for a method of pipetting liquids with various densities and at different temperatures accurately using air displacement. Also, a need exists for improvements in pipette systems and associated pipettes.